Desulfurization system with novel sorbent transfer mechanism

Abstract

A hydrocarbon desulfurization system employing regenerable solid sorbent particulates in a fluidized bed desulfurization reactor. The sulfur-loaded sorbent particulates are continuously withdrawn from the reactor and transferred to a regenerator. A novel solids transport mechanism provides for the safe and effective transfer of the sulfur-loaded sorbent particulates from the high pressure hydrocarbon environment of the reactor to the low pressure oxygen environment of the regenerator.

1 . A process for transporting finely divided solid particulates from a high pressure hydrocarbon environment in a first reaction vessel to a low pressure oxygen environment in a second reaction vessel, said process comprising the steps of: 
 (a) pressurizing a lockhopper to a fill pressure, thereby providing a pressurized lockhopper;    (b) filling said pressurized lockhopper with said solid particulates and hydrocarbons from said high pressure hydrocarbon environment, thereby providing a filled pressurized lockhopper;    (c) depressurizing said filled pressurized lockhopper to a drain pressure, thereby providing a depressurized filled lockhopper;    (d) purging said hydrocarbons in said depressurized filled lockhopper with a purging gas, thereby providing a purged depressurized filled lockhopper; and    (e) transporting said solid particulates from said purged depressurized filled lockhopper to said low pressure oxygen environment, thereby providing a drained depressurized lockhopper, wherein said solid particulates are maintained in the dense phase during said transporting.    
   
   
       2 . A process in accordance with  claim 1 , wherein said transporting is accomplished without the aid of a lift gas.  
   
   
       3 . A process in accordance with  claim 1 , wherein said transporting is accomplished entirely by gravity flow and/or by said drain pressure.  
   
   
       4 . A process in accordance with  claim 1 , wherein said first and second reaction vessels are fluidized bed reactors.  
   
   
       5 . A process in accordance with  claim 1 , further comprising desulfurizing a hydrocarbon-containing feed via contact with said solid particulates in said first reaction vessel.  
   
   
       6 . A process in accordance with  claim 1 , wherein said fill pressure is within 20 percent of the pressure in said high pressure hydrocarbon environment and wherein said drain pressure is within 20 percent of the pressure of said low pressure oxygen environment.  
   
   
       7 . A process in accordance with  claim 6 , wherein the pressure in said high pressure hydrocarbon environment is in the range of from about 50 to about 750 psig and wherein the pressure in said low pressure oxygen environment is in the range of from about 10 to about 250 psig.  
   
   
       8 . A process in accordance with  claim 6 , wherein said drain pressure is at least 50 psi less than said fill pressure.  
   
   
       9 . A process in accordance with  claim 1 , wherein step (a) includes charging a hydrogen-containing gas to said lockhopper and wherein step (d) includes charging an inert gas to said lockhopper.  
   
   
       10 . A process in accordance with  claim 1 , wherein steps (a), (c), (d), and (e) include isolating said lockhopper from said high pressure hydrocarbon environment with an isolating gas and wherein steps (a), (b), (c), and (d) include isolating said lockhopper from said low pressure oxygen environment with said isolating gas.  
   
   
       11 . A process in accordance with  claim 1 , wherein said solid particulates have a mean particle size in the range of from about 20 to about 150 microns and a density in the range of from about 0.5 to about 1.5 g/cc.  
   
   
       12 . A process in accordance with  claim 1 , wherein said solid particulates have a Group A Geldart characterization.  
   
   
       13 . A process in accordance with  claim 1 , further comprising the step of: 
 (f) purging said depressurized drained lockhopper with said purging gas, thereby providing a purged drained depressurized lockhopper.    
   
   
       14 . A process in accordance with  claim 13 , further comprising the step of: 
 (g) purging said purged drained depressurized lockhopper with a hydrogen-containing gas.    
   
   
       15 . A process in accordance with  claim 14 , further comprising the step of: 
 (h) subsequent to step (g), repeating steps (a) through (g).    
   
   
       16 . A process in accordance with  claim 14 , wherein step (a) includes charging said hydrogen-containing gas to said lockhopper, wherein said purging gas is an inert gas, and wherein said hydrogen-containing gas comprises at least 50 mole percent hydrogen.  
   
   
       17 . A process in accordance with  claim 14 , wherein steps (a) through (g) are accomplished in a cycle time in the range of from about 5 to about 30 minutes.  
   
   
       18 . A process in accordance with  claim 14 , wherein step (a) is accomplished in the range of from about 0.2 to about 2 minutes, wherein step (b) is accomplished in the range of from about 1 to about 6 minutes, wherein step (c) is accomplished in the range of from about 0.5 to about 4 minutes, wherein step (d) is accomplished in the range of from about 2 to about 12 minutes, wherein step (e) is accomplished in the range of from about 1 to about 8 minutes, wherein step (f) is accomplished in the range of from 1 to 8 minutes, and wherein step (g) is accomplished in the range of from about 1 to about 6 minutes.  
   
   
       19 . A process in accordance with  claim 1 , wherein step (d) includes passing said purging gas in a first flow direction through a filter at least partly disposed in said lockhopper, wherein said filter is operable to substantially prevent said solid particulates from exiting said lockhopper with said purging gas.  
   
   
       20 . A process in accordance with  claim 19 , wherein step (a) includes passing a pressurizing gas through said filter in a second flow direction generally opposite said first flow direction, thereby cleaning said filter.  
   
   
       21 . A process for transporting finely divided solid particulates from a low pressure oxygen environment in a first reaction vessel to a high pressure hydrogen environment in a second reaction vessel, said process comprising the steps of: 
 (a) depressurizing a lockhopper to a fill pressure, thereby providing a depressurized lockhopper;    (b) filling said depressurized lockhopper with said solid particulates from said low pressure oxygen environment, thereby providing a filled depressurized lockhopper;    (c) purging said filled depressurized lockhopper with a purging gas, thereby providing a purged filled depressurized lockhopper;    (d) pressurizing said purged filled depressurized lockhopper to a drain pressure, thereby providing a pressurized purged filled lockhopper; and    (e) transporting said solid particulates from said pressurized purged filled lockhopper to said high pressure hydrogen environment, wherein said solid particulates are maintained in the dense phase during said transporting.    
   
   
       22 . A process in accordance with  claim 21 , wherein said transporting is accomplished without the aid of a lift gas.  
   
   
       23 . A process in accordance with  claim 21 , wherein said transporting is accomplished entirely by gravity flow and/or by said drain pressure.  
   
   
       24 . A process in accordance with  claim 21 , wherein said first and second reaction vessels are fluidized bed reactors.  
   
   
       25 . A process in accordance with  claim 21 , further comprising reducing said solid particulates in said second reaction vessel via contact with a hydrogen-containing gas.  
   
   
       26 . A process in accordance with  claim 21 , wherein said fill pressure is within 20 percent of the pressure in said low pressure oxygen environment and wherein said drain pressure is within 20 percent of the pressure of said high pressure hydrogen environment.  
   
   
       27 . A process in accordance with  claim 21 , wherein the pressure in said low pressure oxygen environment is in the range of from about 10 to about 250 psig and wherein the pressure in said high pressure hydrogen environment is in the range of from about 50 to about 750 psig.  
   
   
       28 . A process in accordance with  claim 21 , wherein said fill pressure is at least 50 psi less than said drain pressure.  
   
   
       29 . A process in accordance with  claim 21 , wherein step (c) includes charging an inert gas to said lockhopper and wherein step (d) includes charging a hydrogen-containing gas to said lockhopper.  
   
   
       30 . A process in accordance with  claim 21 , wherein steps (a), (c), (d), and (e) include isolating said lockhopper from said low pressure oxygen environment with an isolating gas and wherein steps (a), (b), (c), and (d) include isolating said lockhopper from said high pressure hydrogen environment with said isolating gas.  
   
   
       31 . A process in accordance with  claim 21 , wherein said solid particulates have a mean particle size in the range of from about 20 to about 150 microns and a density in the range of from about 0.5 to about 1.5 g/cc.  
   
   
       32 . A process in accordance with  claim 21 , wherein said solid particulates have a Group A Geldart characterization.  
   
   
       33 . A process in accordance with  claim 21 , further comprising the step of: 
 (f) between steps (a) and (b), purging said depressurized lockhopper with said purging gas.    
   
   
       34 . A process in accordance with  claim 33 , further comprising the step of: 
 (g) between steps (c) and (d), purging said purged filled depressurized lockhopper with a hydrogen-containing gas.    
   
   
       35 . A process in accordance with  claim 34 , further comprising the step of: 
 (h) subsequent to step (g), repeating steps (a) through (g).    
   
   
       36 . A process in accordance with  claim 34 , wherein step (d) includes charging said hydrogen-containing gas to said lockhopper, wherein said purging gas is an inert gas, and wherein said hydrogen-containing gas comprises at least 50 mole percent hydrogen.  
   
   
       37 . A process in accordance with  claim 34 , wherein steps (a) through (g) are accomplished in a cycle time in the range of from about 5 to about 30 minutes.  
   
   
       38 . A process in accordance with  claim 34 , wherein step (a) is accomplished in the range of from about 0.5 to about 4 minutes, wherein step (b) is accomplished in the range of from about 1 to about 6 minutes, wherein step (c) is accomplished in the range of from about 1 to about 8 minutes, wherein step (d) is accomplished in the range of from about 0.2 to about 2 minutes, wherein step (e) is accomplished in the range of from about 1 to about 8 minutes, wherein step (f) is accomplished in the range of from 1 to 10 minutes, and wherein step (g) is accomplished in the range of from about 1 to about 6 minutes.  
   
   
       39 . A process in accordance with  claim 21 , wherein step (c) includes passing said purging gas in a first flow direction through a filter at least partly disposed in said lockhopper, wherein said filter is operable to substantially prevent said solid particulates from exiting said lockhopper with said purging gas.  
   
   
       40 . A process in accordance with  claim 39 , wherein step (d) includes passing a pressurizing gas through said filter in a second flow direction generally opposite said first flow direction, thereby cleaning said filter.  
   
   
       41 . A method for controlling the transfer of solid particulates from a first vessel to a second vessel via a solids conduit, said method comprising the steps of: 
 (a) adjusting a first valve fluidly disposed in said solids conduit to thereby control the flow rate of said solid particulates through said first valve;    (b) adjusting the pressure in at least one of said first and second vessels to thereby control the differential pressure across said first valve; and    (c) measuring the differential pressure across said first valve using a differential pressure indicator.    
   
   
       42 . A method in accordance with  claim 41 , further comprising measuring the pressure in said second vessel.  
   
   
       43 . A method in accordance with  claim 42 , wherein step (b) is performed in response to the measured differential pressure across said first valve and the measured pressure in said second vessel.  
   
   
       44 . A method in accordance with  claim 41 , further comprising substantially continuously withdrawing said solid particulates from said first vessel.  
   
   
       45 . A method in accordance with  claim 41 , wherein step (b) includes adjusting a second valve fluidly disposed in a fluids conduit that fluidly communicates with said first and second vessels.  
   
   
       46 . A method in accordance with  claim 41 , wherein said first valve is a slide valve and wherein said second valve is a pressure controlling valve.  
   
   
       47 . A method in accordance with  claim 41 , wherein step (b) is performed in response to the differential pressure measured in step (c).  
   
   
       48 . A method in accordance with  claim 47 , wherein step (b) includes controlling the pressure in said second vessel by adjusting a second valve fluidly disposed in a fluids conduit fluidly communicating with said first and second vessels.  
   
   
       49 . A system for controlling the flow of solid particulates from a first vessel to a second vessel, said system comprising: 
 a solids conduit fluidly communicating with said first and second vessels and operable to transfer said solids particulates from said first vessel to said second vessel;    a first valve fluidly disposed in said solids conduit and operable to control the flow of said solid particulates therethrough;    a fluids conduit fluidly communicating with said first and second vessels and operable to transfer fluids from said second vessel to said first vessel;    a second valve fluidly disposed in said fluids conduit and operable to control the flow of said fluids from said second vessel to said first vessel, thereby controlling the pressure in said second vessel; and    a differential pressure indicator operable to measure the differential pressure across said first valve.    
   
   
       50 . A system in accordance with  claim 49 , further comprising: 
 a pressure controller operable to measure the pressure in said second vessel and adjust said second valve to maintain a desired pressure in said second vessel.    
   
   
       51 . A system in accordance with  claim 50 , further comprising: 
 an electronic control device operably communicating with said differential pressure indicator and said pressure controller and programmed to determine said desired pressure based on the differential pressure measured by said differential pressure indicator.    
   
   
       52 . A system in accordance with  claim 51 , wherein said electronic control device provides said desired pressure to said pressure controller.  
   
   
       53 . A process in accordance with  claim 1 , wherein said purging gas is introduced into said lockhopper after said depressurizing of step (c).  
   
   
       54 . A process in accordance with  claim 17 , wherein said transporting of step (e) is carried out after said purging of step (c).